Stock material or miscellaneous articles – Composite – Of quartz or glass
Reexamination Certificate
1999-12-10
2001-05-22
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Composite
Of quartz or glass
C359S359000, C359S360000, C359S580000, C359S588000, C359S589000, C428S336000, C428S343000, C428S344000, C428S212000, C428S216000, C428S428000, C428S432000, C428S697000, C428S699000, C428S701000, C428S702000
Reexamination Certificate
active
06235398
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a transparent laminate and a filter using the transparent laminate for use in a plasma display panel (hereinafter referred to as PDP). Particularly, it relates to a PDP filter disposed on the front surface of a PDP which has a basic function of simultaneously cutting electromagnetic waves and near-infrared rays theoretically generated from the PDP and which is superior in visible light transmission characteristic, visible light low reflection characteristic and surface mar-proofness, and a PDP display unit and a PDP front plate provided with the filter stuck thereto.
The present application is based on Japanese Patent Application No. Hei. 10-352219, which is incorporated herein by reference.
2. Description of the Related Art
Transparent laminates each having a metal thin film layer put between transparent dielectric film layers have been discussed with the advance of thin-film-forming technology represented by a vacuum vapor deposition method or a sputtering method. These transparent laminates can utilize both electrically conducting characteristic and infrared reflection characteristic of the metal thin film layer and can provide a function of preventing reflection of visible light on a metal surface by means of the transparent dielectric film layers. For example, these transparent laminates are used in transparent heat-insulating materials for solar cells, green houses for agriculture, window materials for buildings, show-cases for food, and so on, because these transparent laminates transmit visible light rays and reflect heat rays. Further, these laminates are used suitably in electrodes for liquid-crystal displays, electrodes for field light-emitters, electromagnetic wave shielding films, antistatic films, and so on, because these laminates are transparent and exhibit high electrically conducting characteristic. The configurations of these transparent laminates are disclosed, for example, in Japanese Patent Publications No. Sho. 55-11804, Hei. 9-176837, and so on.
On the other hand, with respect to display technology, a plasma display panel (hereinafter referred to as PDP) has been developed as a large-screen display in compliance with the wishes of reduction of thickness and weight and increase of screen size.
The PDP generates electric discharge in a gas mainly containing a rare gas, especially neon, enclosed in the panel. Fluorescent substances of R, G and B applied on cells in the panel are made to emit light by vacuum ultraviolet rays generated by the electric discharge. In this light-emitting process, electromagnetic waves and near-infrared rays unnecessary for the operation of the PDP are emitted simultaneously. Particularly, electromagnetic waves not only cause malfunctions of peripheral devices but also have a bad influence on human bodies. Accordingly, it is necessary to cut the electromagnetic waves.
Further, the wave length of the near-infrared rays emitted is in a range of from 850 to 1200 nm. On the other hand, the light-receiving sensitivity of remote controllers for domestic electrification products, karaoke, audio and video appliances, and so on, is in a range of from 700 to 1300 nm. There arises a problem that near-infrared rays emitted from the PDP cause the malfunctions of the remote controllers. Accordingly, it is necessary to cut the intensive near-infrared rays theoretically generated from the PDP.
Therefore, a filter capable of simultaneously cutting electromagnetic waves and near-infrared rays generated from the PDP has been discussed. For example, a plate, or the like, formed by sticking or thermally fusion-bonding an acrylic sheet having metal mesh or etching mesh embedded therein to an acrylic sheet mixed with a dye type material for absorbing near-infrared rays has been heretofore used as the filter. The mesh type filter was easy to obtain a low surface resistance value. The mesh type filter, however, had a problem in image blurring due to a moire phenomenon generated between pixel pitch and electrically conductive mesh, durability of a near-infrared absorbing material, and so on. Further, the amount of the near-infrared absorbing material to be added needed to increase in order to improve the near-infrared cut factor. With the increase of the amount of the near-infrared absorbing material, however, the defects of lowering of the visible light transmission factor and occurrence of color-eye could not be avoided.
On the other hand, application of the aforementioned transparent laminate to a PDP filter has been discussed. It is however the existing circumstances that it is impossible to obtain any transparent laminate which can sufficiently satisfy various characteristics such as electromagnetic wave shielding characteristic, near-infrared cutting characteristic, visible light transmission characteristic, low reflection characteristic, low surface resistance, and so on, with a comparatively simple configuration.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a transparent laminate especially suitably used as an optical basic member in a PDP filter, and a light and thin-type PDP filter which satisfies various characteristics such as electromagnetic wave shielding characteristic, near-infrared cutting characteristic, visible light transmission characteristic, visible light low reflection characteristic, low surface resistance, surface mar-proofness, and so on, required by the PDP filter and which is good in visual recognition characteristic. Another object of the present invention is to provide a PDP display unit and a PDP front plate provided with the PDP filter.
As a result of eager discussion in order to solve the above objects, the present inventors have attained the invention which is a transparent laminate comprising: a transparent substrate; a low refractive index transparent film formed on a surface of the transparent substrate; n units (3≦n≦5) of high refractive index transparent films and silver type transparent electrical conductor -films each unit consisting of high refractive index transparent films and silver type transparent electrical conductor films, the n units being laminated successively on a surface of the low refractive index transparent film; another high refractive index transparent film formed on a surface of the n units; and another low refractive index transparent film formed on a surface of the other high refractive index transparent film, wherein each of the low refractive index transparent films is an optically transparent film having a refractive index n
L
in a range of from 1.3 to 1.6 and each of the high refractive index transparent films is an optically transparent film having a refractive index n
H
in a range of from 1.9 to 2.5.
In the above optical condition, it is preferable to satisfy the condition that the thickness of the low refractive index transparent film formed on a surface of the transparent substrate is 1×(&lgr;/4n
L
), the thickness of the low refractive index transparent film in the outermost layer is 2×(&lgr;/4n
L
), the thickness of each of the high refractive index transparent films adjacent to the low refractive index transparent films is (1/2)×(&lgr;/4n
H
), the thickness of each of the high refractive index films sandwiched between the silver type transparent electrical conductor films is 1×(&lgr;/4n
H
) and the thickness of each of the silver type transparent electrical conductor films is (1/5)×(&lgr;/4n
H
)×(n
H
−1) when the optical center wavelength &lgr; is 550 nm. In this condition, the thickness change of each of the low refractive index transparent films, the high refractive index transparent films and the silver type transparent electrical conductor films may be in a range of ±20%.
In this invention, it is preferable that the high refractive index transparent film is a thin film made from one compound or two or more compounds selected from the group consisting of indium oxide, tin oxide, titanium dioxide, cerium oxid
Hieda Yoshihiro
Miyauchi Kazuhiko
Nakamura Toshitaka
Sasa Kazuaki
Jones Deborah
McGinn & Gibb PLLC
Miranda Lymarie
Nitto Denko Corporation
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