Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-08-19
2001-10-02
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
active
06297310
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a barrier rib composition for a plasma display panel and more particularly to a barrier rib composition for a plasma display panel that is adapted to have a high molding property at a low pressure.
2. Description of the Related Art
As shown in
FIG. 1
, a conventional plasma display panel of alternating current driving system (hereinafter, AC-system PDP) includes a lower glass substrate
10
mounted with an address electrode
12
, and an upper glass substrate
20
mounted with a transparent electrode pair
22
. A desired thickness of lower dielectric thick film
14
for forming a wall charge and a barrier rib
16
for dividing discharge cells are sequentially formed on the lower glass substrate
10
mounted with the address electrode
12
. A desired thickness of fluorescent film
18
is coated on the surface of the lower dielectric thick film
14
and the wall surface of the barrier rib
16
. This fluorescent film
18
is radiated by an ultraviolet ray generated during the plasma discharge to generate a visible light. Meanwhile, an upper dielectric thick film
24
and a protective film
26
are sequentially formed on the bottom surface of the upper glass substrate
20
mounted with the transparent electrode pair
22
. The upper dielectric thick film
24
forms a wall charge like the lower dielectric thick film
14
, and the protective film
26
protects the upper dielectric thick film
24
from an impact of a gas ion during the plasma discharge. Such an AC-system PDP has discharge cells formed by isolating the lower and upper glass substrates
14
and
16
through the barrier rib
8
. He+Xe mixture gas or Ne+Xe mixture gas is sealed into the discharge cells.
The barrier rib has more and more made into a high detailed shape in accordance with a tendency to apply a PDP to a high-resolution display. In other words, since a space become smaller as a resolution of the panel increases, it is necessary to form the barrier rib at a high level so as to improve the efficiency. Accordingly, the barrier rib requires a high aspect ratio having a narrow width and a great height. In order to meet such a requirement, there has been suggested the low temperature co-fired ceramic on metal(LTCCM) system that is capable of simplifying the process as well as fabricating a high detailed barrier rib having a high aspect ratio.
Referring to
FIGS. 2A
to
2
F, there is shown a method of fabricating a barrier rib according to the conventional LTCCM system step by step. First, a green sheet
30
is formed. Barrier rib material slurry is prepared in the first process. The barrier rib material slurry is prepared by mixing a barrier rib composition at a component ratio as indicated in the following Table:
TABLE 1
Barrier Rib Composition and Component Ratio
Composition
Component Ratio (weight %)
Glass Powder
70
Solvent
24
Plasticizer
2
Binder
3
Additive
1
wherein the component ratio is calculated assuming that a weight of glass be 100 weight %. As seen from the Table 1, the conventional barrier rib composition contains 70 weight % glass powder, 24 weight % solvent, 2 weight % plasticizer, 3 weight % binder and 1 weight % additive. The barrier rib material slurry is prepared by mixing the barrier rib composition at a component ratio in the Table 1. The barrier rib composition keeps a liquid state and is used for a tape casting.
Such a barrier rib composition is largely divided into an inorganic substance and an organic substance. The glass powder corresponds to the inorganic substance while the solvent, the plasticizer, the binder and the additive correspond to the organic substance. A function of the organic substance will be described in detail. The binder binds the glass powder and keeps a viscosity of the glass powder. Poly-Vinyl-Butyral(PVB) is used as the binder. The plasticizer prevents the green sheet
30
from being hardened easily to give certain flexibility to the green sheet
30
. Butyl-Benzyl-Pthalate(BBP) is used as the plasticizer. The solvent is responsible for melting the binder and the plasticizer. Ethanol or Methyl-Ethyl-Ketone(MEK) is used as the solvent. The additive includes a dispersant and a surfactant so as to prevent a conglomeration of the powder. Fish oil is used as the additive.
Meanwhile, an organic substance component ratio of the barrier rib is indicated in the following Table:
TABLE 2
Organic Substance Component Ratio of Barrier Rib
Composition
Component Ratio (weight %)
Solvent
82
Plasticizer
6
Binder
9
Additive
3
wherein the component ratio is calculated assuming that a weight of the organic substance be 100 weight %. As seen from the Table 2, the organic substance of the conventional barrier rib contains 82 weight % solvent, 6 weight % plasticizer, 9 weight % binder and 3 weight % additive.
In the second process, a desired thickness of green sheet
30
is prepared by putting the barrier rib material slurry into a tape casting device(not shown). The green sheet
30
prepared by such a process is shown in FIG.
2
A.
Next, the green sheet
30
is disposed on a substrate
32
. The green sheet
30
is deposited on the upper part of the substrate
32
having a desired thickness(e.g., 0.5 mm). The substrate
32
is made from glass, glass-ceramic, ceramic and metal, etc. Particularly, Titanium having a thickness of 0.5 mm to 1 mm is mainly used as the metal. The green sheet
30
disposed on the upper part of the substrate
32
is shown in FIG.
2
B.
Subsequently, an electrode
36
is formed on the green sheet
30
. The electrode
36
is formed by putting the green sheet
30
deposited on the substrate
32
into a printer(not shown). The electrode
36
formed on the upper part of the green sheet
30
is shown in FIG.
2
C.
Next, an electrode protective layer
34
is formed on the upper part of the electrode
36
. The electrode protective layer
34
protects the electrode
36
from a sputtering caused by the discharge, and accumulates an electric charge produced by the discharge to lower a driving voltage. The electrode protective layer
34
formed on the upper part of the electrode
36
is shown in FIG.
2
D.
Finally, a barrier rib
40
is formed by positioning a mold
38
with a shape of barrier rib on the upper part of the substrate
32
and then applying a desired pressure thereto. The barrier rib
40
is molded at the green sheet
30
by positioning the mold
38
having a hole
38
a
in a shape of barrier rib on the upper part of the substrate
32
and then applying a desired pressure thereto. In this case, a pressing is made between the mold
38
and the substrate
32
, or a desired pressure is applied by means of a roller and the like. At this time, the green sheet
30
is moved into the hole
38
a
for a formation of the barrier rib by a pressure applied to the mold
38
and is molded into a shape of barrier rib. For instance, a pressure of 130 kgf/cm
2
is applied in the molding process. This results from a fact that a barrier rib having a size intended by a manufacturer can not be made until a hardening is rapidly progressed by a component ratio of the green sheet
30
so as to apply a high pressure. The process of molding the barrier rib is shown in FIG.
2
E. Also, the barrier rib
40
in which a molding is completed is plasticized at a desired temperature. The barrier rib
40
formed by the plasticization is shown in FIG.
2
F.
As described above, the prior art has a problem in that, since a deformation of the substrate is caused when a high pressure is applied to form the barrier rib, a performance of the PDP is deteriorated. Thus, it is necessary to provide a barrier rib composition having an excellent molding property at a low pressure.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a barrier rib composition for a plasma display panel that is adapted to have a high molding property at a low pressure.
In order to achieve these and other objects of the invention, a barrier rib composition for a high-brightness plasma display panel accor
Jang Woo Sung
Kim Je Seok
Cain Edward J.
Fleshner & Kim LLP
LG Electronics Inc.
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