Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
1998-10-22
2001-01-23
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S637000
Reexamination Certificate
active
06177762
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma address information display device used for a display apparatus and the like.
2. Description of the Related Art
The development of information display devices such as flat panel displays has already passed through the stage of small-size, monochrome devices realizing binarization, and proceeded to the stage of large-size, colored devices, gray-scale display and moving-image displays. The performance of such advanced information display devices has been improved year by year.
The configuration of a plasma address liquid crystal display device as one of such conventional information display devices will be described with reference to FIG.
5
.
Referring to
FIG. 5
, the plasma address liquid crystal display device
300
includes a color filter substrate
30
A, a plasma address cell
30
B, and a liquid crystal layer
26
formed by injecting a liquid crystal material in a space between the color filter substrate
30
A and the plasma address cell
30
B. A backlight
32
is disposed on the surface of the plasma address cell
30
B opposite to the surface thereof in contact with the liquid crystal layer
26
.
The color filter substrate
30
A includes a polarizing plate
21
a
, a transparent substrate
22
a
, color filters
23
, transparent electrodes
24
, and an alignment film
25
a
. The plasma address cell
30
B includes a polarizing plate
21
b
, a transparent substrate
22
b
, partitions
28
, anodes
29
A and cathodes
29
C as plasma discharge electrodes, a transparent thin substrate
27
, and an alignment film
25
b.
A rare gas such as He, Ne, Ar, Xe, or the like is sealed in a plurality of plasma discharge spaces
31
each surrounded by the transparent substrate
22
b
, the adjacent partitions
28
, and the transparent thin substrate
27
. The pressure of the rare gas in the plasma discharge spaces
31
is in the range of 10 to 10
4
Pa, preferably in the range of 10
2
to 5×10
3
Pa.
The conventional plasma address liquid crystal display device with the configuration described above has problems as follows, as disclosed in “IDW '96, LA1-3, p.423”. Metal particles of the anodes
29
A and the cathodes
29
C as the plasma discharge electrodes may attach to the transparent thin substrate
27
due to a sputtering phenomenon occurring during plasma generation. The attachment of metal particles reduces the transmittance of the transparent thin substrate
27
and thus the plasma address liquid crystal display device
300
, and also makes the transparent thin substrate
27
conductive, thereby generating color mixing.
SUMMARY OF THE INVENTION
The plasma address information display device of this invention includes a plasma address cell and a display medium layer which is addressed by the plasma address cell, the plasma address cell including: a substrate; a transparent thin substrate opposing to the substrate; a plurality of partitions made of dielectrics formed between the substrate and the transparent thin substrate; and electrodes disposed on a surface of the substrate facing the transparent thin substrate, wherein a mixed gas composed of an inactive gas and an active gas is sealed in plasma discharge spaces each surrounded by the substrate, the transparent thin substrate, and the plurality of partitions.
In one embodiment of the invention, the inactive gas includes at least one type of gas selected from the group consisting of He, Ne, Ar, and Xe, and the active gas includes at least one type of gas selected from the group consisting of N
2
and O
2
.
In another embodiment of the invention, a gas pressure of the mixed gas sealed in the plasma discharge spaces is in the range of 10 to 10
4
Pa.
In still another embodiment of the invention, the electrodes are composed of anodes and cathodes, and a voltage for generating plasma discharge is applied to the cathodes.
In still another embodiment of the invention, the plasma address information display device further includes an additional substrate located on a surface of the display medium layer opposite to a surface thereof in contact with the plasma address cell, wherein color filters and transparent electrodes are formed on the additional substrate, and a data voltage for writing data is applied to the transparent electrodes.
In still another embodiment of the invention, the plasma discharge spaces extend in a first direction and the transparent electrodes extend in a second direction crossing the first direction, and portions where the plasma discharge spaces and the transparent electrodes spatially overlap each other correspond to pixel regions of the plasma address information display device.
In a plasma address information display device of the present invention, a mixed gas composed of an inactive gas and an active gas is sealed in plasma discharge spaces each surrounded by a substrate, a thin substrate, and insulators disposed between the substrates. Metal particles sputtered from the electrodes in the plasma discharge spaces during plasma generation react with the active gas existing in the plasma discharge spaces before reaching to the thin substrate. Therefore, the reacted metal particles, not the metal particles themselves, attach to the thin substrate.
When N
2
and O
2
are used as the active gas, the metal particles sputtered from the electrodes react with the active gas to form a dielectric such as a nitride and an oxide. The dielectric is transparent unlike the metal. Therefore, the reduction of the transmittance can be prevented. In addition, this prevents the surface of the thin substrate from being made conductive, and thus prevents the generation of color mixing. Using N
2
and O
2
as the active gas is also advantageous in that these gases do not adversely affect a plasma state generated in the plasma discharge spaces.
The gas pressure of the mixed gas should preferably be in the range of 10 to 10
4
Pa to provide a stable plasma state.
Furthermore, the existence of the active gas added to the plasm channel is considered to have caused the penning effect, causing the function of shortening the decay time of the plasma channel.
Thus, the invention described herein makes possible the advantage of providing a plasma address information display device capable of shortening the decay time, preventing reduction of the transmittance, and preventing the generation of color mixing.
This and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.
REFERENCES:
patent: 3716742 (1973-02-01), Nakayama et al.
patent: 3801851 (1974-04-01), Andoh et al.
patent: 3811061 (1974-05-01), Nakayama et al.
patent: 3944875 (1976-03-01), Owaki et al.
patent: 4147958 (1979-04-01), Ahearn et al.
T. Morita, et al, “Application of PALC Technology to 25-in. Full-Color Display”, IDW '96, LA1-3, 1996, pp. 423-426.
Nixon & Vanderhye P.C.
Patel Vip
Sharp Kabushiki Kaisha
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