Gas discharge display

Details Gas discharge display Gas discharge display

1998-09-11

2001-02-27

Patel, Nimeshkumar D. (Department: 2879)

Electric lamp and discharge devices

With gas or vapor

Three or more electrode discharge device

C313S581000

Reexamination Certificate

active

06194831

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gas discharge display, and more particularly, to a gas discharge display for use in a PDP(Plasma Display Panel), in which a discharge region is filled with 4 kind of gases mixed at a particular ratio, for improving a reliability of a product.
2. Discussion of the Related Art
In general, there are a DC type, an AC type, and a hybrid type, a combination of the DC type and the AC type, in the gas discharge display in view of electrode structure. The DC type and the AC type differ in that whether the electrode is exposed directly to discharge plasma or indirectly through a dielectric layer. In the case of the DC type PDP, the electrode is exposed directly to the discharge plasma, and, in the case of the AC type PDP, the electrode joins with the discharge plasma indirectly through the dielectric layer. This difference leads to show a difference in discharge. In the case of the AC type PDP, charged particles formed from discharges are accumulated on the dielectric layer. That is, electrons are accumulated on the dielectric layer over an electrode having a positive potential charged thereto, and ions are accumulated on the dielectric layer over an electrode having a negative potential charged thereto. A potential formed by this phenomenon is called as a wall potential, which has a polarity opposite to an external potential, to lower a potential applied to a gas in a cell once the wall potential is started to form. Accordingly, an adequate wall potential is formed, the potential applied to the gas is lowered below a level at which a sustaining of the discharge is possible no more, the discharge is canceled. However, if the polarity of the potential applied to the external electrode is changed after the wall potential is formed, the potential applied externally will be added on top of the wall potential, allowing the AC type PDP operative according to a memory function in which a discharge can be made even if a low external potential is applied. Thus, the AC type PDP has the memory function due to the wall potential accumulated on the dielectric layer. That is, a cell having a discharge made previously to form a wall potential on the dielectric in the cell can make a discharge at a voltage lower than a cell without the wall potential. This memory function is very useful characteristic for operating a large sized PDP, a gas discharge display employing line driving system. Different from the AC type PDP, since the DC type PDP has no function of the wall potential formation on the dielectric, it has no intrinsic memory function. That is, as the electrode is directly exposed to a discharge region, charged particles from the discharge flow to external circuits through electrodes of opposite polarities, without any accumulation of the charged particles on electrode surfaces. However, in the case of the DC type PDP, a pulse memory function in which a charged particle supply effect is employed is used. The pulse memory function employs a principle that a discharge can be made at a voltage lower than a case when there are no charged particles, and quasi neutral particles if a discharge pulse is applied before the charged, and quasi neutral particles formed from a previous discharge are attenuated. This memory function is an essential feature for allowing operation of a large sized panel in the line driving system without loss of luminance and is also required in view of an electrode structure.
FIGS. 1 and 2
illustrate sections showing basic electrode structures of the DC type PDP and the AC type PDP, respectively.
Referring to
FIG. 1
, the basic electrode structure of the DC type PDP is provided with an anode
3
and cathode
4
on a front substrate
1
and a back substrate
2
respectively, barrier ribs
5
, and a fluorescent material layer
6
. The anode
3
and the cathode
4
forms a current path for forming a discharge. The barrier rib
5
fixes a distance between electrodes for forming the discharge, and prevent a crosstalk caused by a discharge in an adjacent cell. In the DC type PDP, nickel is mostly used as an electrode material, which has a high secondary electron emission coefficient for providing a low discharge voltage characteristic and an excellent anti-sputter characteristic endurable on ion sputtering. And, the AC type PDP shown in
FIG. 2
is provided with a dielectric layer
10
each covering sustain electrodes
7
and
8
and an address electrode
9
for forming a capacitance coupled discharge. In general, the dielectric layer is formed of a material to selected from borosilicate group coated with a thin film of oxide, such as magnesium oxide, as a protection film
11
because the dielectric layer
10
of borosilicate group has a lower secondary electron emission coefficient and a short lifetime against sputtering of ions in the plasma. The magnesium oxide MgO has a good anti-sputter characteristic, but also a high secondary electron emission coefficient that provides a low voltage characteristic. However, since the magnesium oxide layer should be thin and have an excellent surface characteristic, the magnesium oxide layer is in general formed by a thin film formation process of vacuum deposition, rather than thick film formation in printing. The barrier rib
5
is required to have a height of 100~200 &mgr;m for maintaining discharge distance and volume. As one layer of thick film printing is a few tens of &mgr;m, the barrier rib
5
may be form by multi-layers of the thick film printing. And, though a number of electrodes required for a discharge is two, in general an electrode structure with three electrodes is mostly used. The DC type PDP has an additional supplementary cathode for forming a supplementary discharge, and the AC type PDP is introduced of an address electrode
9
for separating the sustain electrodes
7
and
8
from a selective discharge and sustain discharge to improve an address speed. Accordingly, the electrode structures may be classified as a two electrode structure and a three electrode structure according to a number of electrodes. Or, the electrode structures may be classified as an opposite type electrode structure and a surface discharge type electrode structures. In the opposite type electrode structure, two sustain electrodes for occurring a discharge are disposed on the front substrate and the back substrate respectively to cause a discharge formed vertical to the panel, and, in the surface discharge type electrode structure, the two sustain electrodes for occurring a discharge are disposed on the same substrate, to form a discharge on one plane of the panel.
FIG. 3
illustrates a perspective view of a background art AC type PDP, provided with a front substrate
1
form of glass for easy transmission of a light, sustain electrodes
7
and
8
each composed of a transparent electrode and a metal electrode on a top surface of the front substrate
1
disposed in a transverse direction at fixed intervals for sustaining a discharge voltage, a dielectric layer
10
formed on an entire surface of the front substrate
1
inclusive of the sustain electrodes
7
and
8
for protecting the sustain electrodes
7
and
8
, a protection layer for protecting the dielectric layer
10
to prolong a lifetime of the dielectric layer
10
, improving a secondary electron emission effect, and reducing variation of a discharge characteristic, a back substrate
2
, a lower base film
12
on an entire top surface of the back substrate
2
, address electrodes
9
on the lower base film
12
formed in a direction perpendicular to the sustain electrodes
7
and
8
at fixed intervals, a white back
13
formed on an entire surface of the lower base film
12
inclusive of the address electrodes
9
, barrier ribs formed between, and in parallel to underlying address electrodes
9
for maintaining a space between the front substrate
1
and the back substrate
2
and preventing unwanted discharge between cells, and R, G, B fluorescent material layers
6
formed between the barrier ribs

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