Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
2000-06-28
2002-10-29
Kim, Robert H. (Department: 2882)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S495000, C313S582000
Reexamination Certificate
active
06472821
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an AC plane discharge type plasma display panel used as a display device for a display apparatus such as monitor and, more particularly, to an improvement in reliability and display quality of the AC plane discharge type plasma display panel.
2. Background Art
It is a recent trend that in personal computer, etc., not only display monitor of small size and thin type is demanded, but also display image of high brightness and high definition is increasingly required. To satisfy such requirements, several displays using a plasma display panel as a display device have been heretofore developed in various fields of the art, and some of them have already been put into practical use.
FIG. 9
is a partially perspective view showing a structure of a typical AC plane discharge type plasma display panel (hereinafter referred to as AC plane discharge type PDP).
In the drawing, reference numeral
1
indicates a transparent electrode, numeral
2
indicates a bus electrode of a metal for supplying a voltage to the transparent electrode
1
, and numeral
11
indicates a fundamental insulating film (hereinafter referred to simply as insulating film) in which light transmission is less lowered. Numeral
3
indicates an even dielectric layer covering the transparent electrode 1 and the bus electrode
2
, and numeral
4
indicates a MgO vapor deposition film (hereinafter referred to as cathode film) serving as a cathode at the time of discharge. Numeral
5
indicates a front glass substrate on which the transparent electrode
1
, bus electrode
2
, dielectric layer
3
and cathode film
4
formed on the insulating film
11
are mounted. These elements form a first substrate section.
Reference numeral
6
indicates a write electrode perpendicularly grade-separating the bus electrode
2
, numeral
10
indicates an even graze layer covering the write electrode
6
, and numeral
7
indicates a barrier rib for partitioning each individual write electrode
6
. Numeral
8
indicates a fluorescent substance formed on the surface of the graze layer
10
and on the wall surface of the barrier rib
7
, and subscripts R, G and B means that the fluorescent substances respectively emit fluorescent colors of red, green and blue. Numeral
9
indicates a rear glass substrate on which the mentioned elements
6
,
7
,
8
and
10
are mounted. These elements form a second substrate section.
Top part of the barrier rib
7
is in contact with the cathode film
4
, whereby a discharge space surrounded by the fluorescent substance
8
and the cathode film
4
is formed. This discharge space is filled with a gas mixture of Xe and Ne.
In this construction, as shown in the drawing, a n-th canning line is formed by a pair of transparent electrode
1
and bus electrode
2
, i.e., by a pair of electrodes Xn and Yn which sustain discharge.
Each junction at which each scanning line and write electrode
6
are grade-separated forms one discharge cell, and an AC plane discharge type PDP is formed such that a large number of discharge cells are arranged in the form of a matrix.
Generally, as disclosed in the Japanese Laid-Open Patent Publication (unexamined) 95382/1988, a glass substrate used as the front glass substrate
5
or the rear glass substrate
9
in the mentioned AC plane discharge type PDP is a soda lime glass containing about 10 to 20 weight % of sodium oxide, a glass of high distortion point containing less sodium oxide and less influenced by thermal distortion, or others.
In the front glass substrate
5
, on the fundamental insulating film
11
of less reduction in light transmittance formed on the surface, a sustain electrode comprising the transparent electrode
1
and the bus electrode
2
is formed by printing process or photolithography mechanical process.
FIG. 10
is a sectional view taken along the line A-A′ in FIG.
9
.
With respect to the front glass substrate
5
of the AC plane discharge type PDP, as shown in
FIG. 10
, a glass substrate formed on the fundamental insulating film
11
of less reduction in light transmittance is generally used.
This is because surface of the glass substrate of the foundation of the transparent electrode
1
is required to be in a condition not containing any sodium oxide, and like structure is popularly adopted in the liquid crystal display (LCD) other than the AC plane discharge type PDP.
The fundamental insulating film
11
performs a function of alkali barrier to prevent that sodium oxide has a negative influence of making unstable the conductivity of the transparent electrode
1
and inhibiting the insulation between the transparent electrodes adjacent each other.
As such a fundamental insulating film
11
, there is a known art in which SiO
2
film, Si
3
N
4
film, Al
2
O
3
film or the like is formed directly on the glass substrate
5
by sputtering or CVD both being a dry film formation method, as disclosed in the Japanese Laid-Open Patent Publication (unexamined) 95382/1988, for example. Generally, SiO
2
film of which formation is easy is popularly adopted in practical use.
In the mentioned construction, the SiO
2
film being the fundamental insulating film
11
is a fundamental film of the transparent electrode
1
which is a transparent conductive film of ITO, SnO
2,
etc., and performs a function of an alkali barrier layer with respect to the front glass substrate
5
.
When the layer of the fundamental insulating film
11
is thicker, effect of the alkali barrier is more improved, which is a tradeoff between the effect of alkali barrier and productivity in the formation of SiO
2
film.
For example, in case of LCD, when adopting a cheap soda lime glass as a base glass substrate, the fundamental SiO
2
film of the transparent electrode performs a necessary and sufficient alkali barrier effect as a result of obtaining a film thickness having values shown in the following Table 1 corresponding to formation method of the SiO
2
film.
TABLE 1
When SiO
2
film is formed by
about 20 (nm)
sputtering
When SiO
2
film is formed by CDV
about 50 (nm)
under normal pressure
When SiO
2
film is formed by
about 100 (nm)
sol-gel method
In this respect, film formation by sputtering is a method for forming a SiO
2
film on a substrate by applying a high voltage (several kV) between a cathode to which SiO
2
target is attached and an anode opposite thereto in vacuum under an atmosphere of argon from 10
−2
Pa to 10
0
Pa, thereby occurring a glow discharge, and by performing a high frequency sputtering.
Film formation by CVD under normal pressure is a method for forming a SiO
2
film by a chemical reaction comprising the steps of heating a substrate, supplying a SiH
4
gas to the surface of the substrate, and decomposing and oxidizing the SiH
4
on the surface of the substrate.
Both sputtering and CVD belong to a dry film formation method. Further, there is a wet film formation method in which a SiO
2
film serving as a alkali barrier film is formed by sol-gel method, as disclosed in the Japanese Laid-Open Patent Publications (unexamined) 303916/1993 and 130307/1995. This film formation by sol-gel method is a method, in which a solution for forming SiO
2
containing a catalyst for accelerating hydrolysis reaction and condensation by applying water to silicon alkoxide such as a monomer (C
2
H
5
O)
4
Si of tetraethoxysilane is applied to a substrate composed of a soda lime glass by dipping, roll coating, etc., thereby forming a film, and after drying the film, a SiO
2
film is obtained by baking at a temperature of about 500.
Also in the AC plane discharge type PDP, on condition hat the transparent electrodes
1
are not coated with a glass material mainly composed of a lead oxide in the display area as in a DC refresh type PDP, for example, and that there is a less potential difference between the transparent electrodes adjacent each other, the SiO
2
film thickness satisfying the mentioned requirements for LCD can perform a sufficient function, even when a soda lime glass containing 10 to
Hirokado Yoshinobu
Nagano Shinichiro
Kim Robert H.
Yun Jurie
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