Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Reexamination Certificate
2002-04-03
2004-11-30
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
C445S059000, C445S010000
Reexamination Certificate
active
06824438
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma display panel, and more particularly, to a plasma display panel, fabricating apparatus and method thereof.
2. Discussion of the Related Art
Today's multimedia demands displays which can represent colors with finer and greater detail with more natural looking images than those of the conventional displays. Specifically, today's CRT (cathode ray tube) or LCD (liquid crystal display) cannot be made into large-scaled display over 40 inches, therefore a plasma display panel (hereinafter abbreviated PDP) is considered to be the next generation display.
Plasma display panels, such as the one shown in
FIG. 1A
, includes upper and lower plates
10
and
20
bonded to each other.
FIG. 1B
illustrates a cross-sectional view of a plasma display panel in
FIG. 1A
, in which the lower plate
20
is rotated at 90° for the convenience of explanation.
The upper plate
10
includes scan electrodes
16
and
16
′ and sustain electrodes
17
and
17
′ formed in parallel with each other, a dielectric layer
11
formed on the upper plate
10
including the scan electrodes
16
and
16
′ and sustain electrodes
17
and
17
′, and a passivation layer
12
on the dielectric layer
11
. The lower plate
20
includes address electrodes
22
, a dielectric film
21
on an entire surface of a substrate including the address electrodes
22
, barrier ribs
23
on the dielectric film
21
between the address electrodes
22
, and a fluorescent material
24
formed on surfaces of the barrier ribs
23
and dielectric film
21
inside in each discharge cell. The space between the upper and lower plates
10
and
20
is charged with a discharge gas mixed with an inert gas such as HE, Xe and the like so as to provide a discharge area.
The PDP operates by igniting the discharge gas. Once a drive voltage is applied a discharge is generated between the address and scan electrodes so that electrons discharged from the inert gas in the discharge cell by the discharge collide with a surface of the passivation layer. Such a collision of electrons causes the electrons to be discharged secondarily from the surface of the passivation layer, then the secondary electrons collide with the plasma gas so as to diffuse the discharge. After the end of the confronting discharge between the address and scan electrodes, wall charges are formed at the surface of the passivation layer on the address and scan electrodes so as to have polarities opposite from each other.
When the drive voltage applied to the address electrode is cut off, the discharge voltage having the opposite polarities is applied continuously to the scan and sustain electrodes. A voltage difference between the scan and sustain electrodes generates a surface electric discharge from the discharge area of the dielectric and passivation layers. The confronting and surface electric discharges make the electrons existing inside the discharge cell collide with the inert gas in the discharge cell. Resultingly, the inert gas in the discharge cell becomes excited so as to generate a UV-ray having a wavelength of 147 nm in the discharge cell. Such a UV-ray collides with the fluorescent material surrounding the barrier ribs and address electrode so as to realize an image.
Hence, in order to make PDP give full play to its performance and extend its endurance, the panel should have strong layers as well as no impurity gas inside.
For convenience, a fabrication method of such PDP is mainly divided into a pre-process, an after-process, and a module process.
First, various layers are formed on the upper and lower plates
10
and
20
in the pre-process. And, the after-process includes a bonding step of the upper and lower plates
10
and
20
, electric discharge gas injection and tip-off steps, an aging step, and a checking step. In this case, ‘tip-off’ is the step of sealing an exhaust pipe by melting after the completion of exhaust and electric discharge gas injection through the exhaust pipe, and ‘aging’ is the step of applying a power to electrodes for a predetermined time to drive so as to remove impurities finally as well as realize an electric discharge voltage drop effect. Circuits and packages are then assembled so as to complete the PDP in the module process.
FIG. 2
illustrates an after-process and process conditions of a plasma display panel according to a related art.
FIG. 3A
to
FIG. 3C
illustrates layouts for a bonding process in
FIG. 2
,
FIG. 4
illustrates a cross-sectional view of an exhaust pipe,
FIG. 5
illustrates a layout of a separative bonding/exhaust apparatus of a plasma display panel according to a related art, and
FIG. 6
illustrates a diagram of a cart in FIG.
5
.
The after-process of PDP according to the related art, as shown in
FIG. 2
, including bonding, exhausting, electric discharge gas injecting, tipping-off, and aging.
First, the upper and lower plates
10
and
20
are transferred to a bonding equipment. Next, a circumference of the upper plate
10
, as shown in
FIG. 3A
, is coated with a sealant
31
, i.e. frit to a predetermined thickness using a dispenser. In this case, frit consists of glass and an additive improving adhesiveness.
A drying is carried out at about 120° C., and then a plasticizing is carried out above 400° C. so as to remove impurities remaining in the frit. Subsequently, the upper and lower plates having completed the plasticizing are transferred to the bonding equipment. In this case, the upper plate
10
is exposed to atmosphere so as to be moved to the bonding equipment.
The upper and lower plates
10
and
20
, as shown in
FIG. 3B
, are aligned with each other in the bonding equipment, and fixed thereto by tongs
32
. The frit is then melted, as shown in
FIG. 3C
, so as to bond the upper and lower plates
10
and
20
to each other.
Additionally, in the bonding step, an exhaust pipe
40
like a straw made of glass, as shown in
FIG. 4
, is attached to an exhaust hole
42
of the lower plate
20
using a frit ring
41
. Subsequently, the panel of which bonding step is completed is transferred to an exhaust and gas injection equipment.
Then, the exhaust and gas injection equipment carries out the exhaust step of discharging externally an impurity gas generated from the layers and impurities adhering to the layers on heating condition at high vacuum using the exhaust pipe
40
formed in the binding step. An electric discharge gas is then injected through the exhaust pipe
40
, and then the tip-off step is carried out in a manner that a tip of the exhaust pipe
40
is heated to melt so as to prevent the injected electric discharge gas from leaking. Finally, a status of the panel is checked after the aging step so as to complete the whole process.
The separative type fabricating equipment in an exhaust type apparatus, which carries out the bonding and exhaust/gas injection steps separately, are divided into the bonding equipment and the exhaust/gas injection equipment. The exhaust/gas injection equipment, as shown in
FIG. 5
, includes a hot wind heating furnace
51
providing conditions for exhaust/electric discharge gas injection and a cart
52
loading the panel
33
as well as unloading the panel after the exhaust/electric discharge gas injection in the hot wind heating furnace
51
.
The cart
52
, as shown in
FIG. 6
, has a complicated structure including a vacuum pump
61
providing a panel with a vacuum state, a vacuum pipe system constructed with an exhaust manifold
62
, valves, ad pipes, an electric discharge gas injection bomb
65
, a gas injection pipe system constructed with a gas injection manifold
63
, valves, and pipes, and a tip-off unit
64
tipping off the exhaust pipe
40
.
Unfortunately, the apparatus and method for fabricating PDP have the following problems or disadvantages.
First, it takes a relatively long time (about 24 hours) to suck out the impurity gas through a several-hundred-microns gap between the bonded upper/lower plates of an at least 40-inch panel a
Lim Jae Ha
Park Bok Yong
Park Se Pyo
Yang Nam Yeol
Fleshner & Kim LLP
LG Electronics Inc.
Macchiarolo Peter
Patel Nimeshkumar D.
LandOfFree
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